Powdered activated carbon treatment (PACT) systems combine biological treatment and carbon adsorption into a single synergistic step. The result is superior pollutant removal efficiencies. The PACT system is typically coupled with a wet air regeneration (WAR) system, which utilizes high temperature and pressure conditions for regenerating spent carbon from the PACT system while simultaneously oxidizing biological solids (when present) accompanying the spent carbon. In an effort to increase the efficiency of pollutant removal to meet increasingly stringent requirements in certain jurisdictions, multi-stage PACT systems have been developed. The principles of two-stage PACT operation have included biodegradable organics removal and some refractory organics removal by carbon absorption in the first stage, and final polishing to low level effluent removal by further carbon absorption in the second stage. Due to the increased footprint, material costs, and operational costs of a multi-stage system relative to a single stage system, more efficient processes and systems are needed.